Structural Basis of Semaphorin-Plexin Recognition and Viral Mimicry from Sema7A and A39R Complexes with PlexinC1

Heli Liu, Z. Sean Juo, Ann Hye Ryong Shim, Pamela J. Focia, Xiaoyan Chen, K. Christopher Garcia, Xiaolin He*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

99 Scopus citations

Abstract

Repulsive signaling by Semaphorins and Plexins is crucial for the development and homeostasis of the nervous, immune, and cardiovascular systems. Sema7A acts as both an immune and a neural Semaphorin through PlexinC1, and A39R is a Sema7A mimic secreted by smallpox virus. We report the structures of Sema7A and A39R complexed with the Semaphorin-binding module of PlexinC1. Both structures show two PlexinC1 molecules symmetrically bridged by Semaphorin dimers, in which the Semaphorin and PlexinC1 β propellers interact in an edge-on, orthogonal orientation. Both binding interfaces are dominated by the insertion of the Semaphorin's 4c-4d loop into a deep groove in blade 3 of the PlexinC1 propeller. A39R appears to achieve Sema7A mimicry by preserving key Plexin-binding determinants seen in the mammalian Sema7A complex that have evolved to achieve higher affinity binding to the host-derived PlexinC1. The complex structures support a conserved Semaphorin-Plexin recognition mode and suggest that Plexins are activated by dimerization.

Original languageEnglish (US)
Pages (from-to)749-761
Number of pages13
JournalCell
Volume142
Issue number5
DOIs
StatePublished - Sep 3 2010

Keywords

  • Molneuro
  • Proteins

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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